While beauty is obviously a subjective matter, many people have made the bold claim of the Saint-Gaudens Double Eagle to hold the title of the world's most beautiful coin. I personally have my doubts about the coin's right to this claim, however, I don't have my doubts about the coins' historical significance.
Augustus Saint-Gaudens was commissioned by Teddy Roosevelt in 1905 as, quite frankly, he hated the current coins. Importantly, Augustus didn't even work at the mint, in fact, the head of the mint kinda hated Augustus after he denounced his artistic ability. Clearly, Augustus was onto something, as most of the public shared his view.
The initial design went through many revisions, such as lady liberty having her wings removed. The most controversial revision was the removal of the motto 'In God we Trust', as Teddy thought that anything relating to the Lord on money amounted to sacrilege. However, this view was not held by the rest of congress, and once it was brought forward to them, it was decided that every coin produced from that point on would have the motto.
While you may not feel as if this coin is the epitome of artistic work, it does hold a special place in the annals of coins for ushering in the new class of 20th century coins.